GST Calculator
GST calculator
Work out what to charge before you send the quote. See how 9% GST changes your price and margin instantly, whether you add it on top or absorb it. Built for founders and finance teams that invoice, bill, and reconcile in Singapore.
How to use this GST calculator
Amount
Enter your amount in SGD
Rate
Keep the prefilled 9% rate, Singapore's current GST rate, or change it for historical or overseas calculations
Add/Remove GST
Choose Add GST if your amount excludes GST, or Remove GST if it already includes it
Result
Read the amount before GST, the GST, and the total, all updated live
GST formulas and worked examples
Singapore's GST rate is 9%
When to charge 9%, 0%, or no GST
If you're GST-registered, you charge output tax on standard-rated sales and claim input tax on business purchases. When you sell to overseas customers, most exports qualify for zero-rating, so you still report the sale but charge 0%. Check the IRAS guidance on when to charge GST for edge cases.
Get the GST right on every invoice
Every standard-rated sale needs a tax invoice that shows the GST separately: your GST registration number, the amount before GST, the GST, and the total. Issue it within 30 days of the supply. Get one number wrong and you're reissuing invoices, fixing credit notes, and reconciling mismatched payments at filing time.
Aspire applies the 9% for you. Invoice management calculates GST on every line item, adds your GST registration number, and sends IRAS-compliant invoices in minutes. Receivable management then matches incoming payments to invoices and chases late payers automatically, so the GST you've charged is the GST you collect.
On the cost side, bill pay and payable management capture the GST on supplier bills, and expense management keeps receipts for input tax claims tidy from day one.
Frequently asked questions
Use the Remove GST option above, or divide the total by 109 and multiply by 9. Two things trip people up in practice. Round the GST to the nearest cent and apply the same rounding method consistently across your invoices. And when a receipt has several line items, work from the final total rather than summing GST per line, since per-line rounding can drift a cent or two from the printed figure.
Multiply the price by 0.09 for the GST, or by 1.09 for the GST-inclusive total. One nuance worth knowing: if you absorb GST instead of adding it to your price, IRAS still treats what you collect as GST-inclusive. You account for output tax at 9/109 of the amount received, and the difference comes out of your margin.
A GST-exclusive price doesn't yet contain GST, so you add 9% on top. A GST-inclusive price already contains it. In Singapore, prices displayed to consumers must be GST-inclusive, while B2B quotes are often exclusive, so always confirm which one you're looking at before you calculate.
Most exports of goods and international services are zero-rated, so you charge 0% but still report the sale in your GST return. The rules depend on where the goods move and where your customer belongs, so check the IRAS zero-rating conditions for your exact case.
Yes. GST-registered businesses claim input tax on purchases made for business use, provided they hold valid tax invoices and the expense isn't blocked, like private car costs. Clean receipt records make these claims painless at filing time.
IRAS requires tax invoices in foreign currency to also show the GST amount and total in SGD, converted using an approved exchange rate such as your bank's selling rate at the time of supply. Invoicing software that stores both currencies saves you the manual conversion.
Yes. Change the rate field to any percentage, like 10% for Australia's GST or 15% for New Zealand's. The prefilled 9% is Singapore's current rate.
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